Being LAX based I can reliably use UA, AA or DL as my core domestic program and I fly enough each year to maintain mid-level elite on any of them. I recently switched away from DL to AA and have been reasonably happy with the product and the service. There are few reasons I can see now to switch away from AA to either of the other two; air travel is getting more expensive, elite status is being diluted (especially at DL) and the whole experience losing its draw for me.
I *love* aviation and I absolutely love to fly. That said, if there is a final straw it won't be one that drives me away from AA into the hands of a competitor. I'll just become loyalty-free and shop around for the absolute best fare that meets my needs, consolidate all my spending with SPG so at least hotel costs are mitigated and in general be a free agent.
To be honest, the introduction of TSA PreCheck and ability to purchase elite seating on all carriers pretty much mitigates the need for me to be elite. If I want to travel in F I'll pay for it.
Until then, I'm going to remain loyal to AA and enjoy the ride as I still find it to be a good program, a good carrier and overall a good blend of services to meet my travel needs.